I bought a 1799 dollar in an NGC holder but the coin moves around a lot inside of the holder and I am afraid it could get damaged. I sent the coin back to be reholdered but I'm still having the same problem. Are large coins more snug inside of a PCGS holder and would therefore prevent movement? Has anyone had luck reholdering an NGC coin in a PCGS holder to prevent movement of the coin? To me the small prongs inside of an NGC holder look less secure.
Interesting. While I can't answer your question, I'd call NGC and let them know this situation and ask if they had different sized core prongs. See if they'd be willing to redo it at no cost. How loose is it? Can you just give a light twist and it moves or does it take a harder jolt? Sometimes a planchet isn't perfectly round and the fourth prong isn't in good contact. I had an ancient come back with no prongs, just a clear center. Maybe that would be an option.
Do you have pictures? If it's a low grade coin it could just be it doesn't fit well in a standard large dollar holder because of wear. Like when an AG wheat cent doesn't fit snug in a coin folder.
Over time I think all coins of all sizes move in their slabs. Since the slabs are plastic they may shrink or expand over time and the condition they were stored under adds to the problem you’re having.
The coin has already been sent in once to be redone. I have already sent in the coin to be reholdered but that didn't solve the problem. I could try asking them if there is a different type of holder that could be used on the coin. The coin is a 1799 dollar BB-161 mid-die state. I wonder if this is a common problem with this particular coin. When I look at the coin in the holder there is a lot of space between the rim and the prongs. Is this common with early American dollars?
While I have no firsthand information, I would expect a larger and heavier coin to potentially move more in the holder, not less than a smaller coin would? Might just be a Bust dollar thing.
I'd say it's highly unlikely that any damage could occur. In the early days PCGS used a holder that came to be known as a "Rattler" because all the coins slabbed in them would rattle if you shook the slab. And I never even heard of one that became damaged because of it. Would your coin still move around in today's PCGS slab ? I don't know because PCGS uses a completely different design (there are no prongs) than NGC. But, it's certainly possible it could. As for what causes the coin to move in the NGC slab, it's because there was some variance in the planchet diameter for the early dollars, they are known for it. If you go here - https://www.cointalk.com/threads/a-coins-weight.371746/ - and look at post #6, you'll see the asterisk that denotes that beside the listed diameter for the early dollars.
Most of the coins that have rotated for me have been small pieces, like half dimes and gold dollars. I have never had a large coin, like a dollar, rotate on me, but I guess there is first time for everything. Since you sent the coin to NGC for a reholder and it's still moving, I'd complain to NGC first and see what they might do. Going to PCGS is a hasstle because that will be a re-grade. If you send it to them in an NGC holder, I can almost gurantee that you will get a lower grade. PCGS is not keen on same grade crossovers even if the coin is good enough to get one.
I did send the coin back to them to be regraded but it didn't make any difference. It seemed better at first but then it started to move around like it did before. When I got the coin back the coin was in almost exactly the same position it was in before which is a little short of turning 45 degrees inside the holder. The good thing is it didn't cost me anymore to get it reholdered because I had won the coin on Heritage Auctions and they had agreed to send the coin back to NGC to be reholdered at no cost to me. I haven't had the same experience as you with PCGS grading coins lower that had previously been graded by NGC but maybe each case is different. I had a 1921 dollar that was graded MS64+ by NGC but when I sent it to PCGS they graded it MS65+. I probably won't send it in to be reholdered by PCGS since as you said they may give the coin a lower grade although to me it looks pretty nice that is unlikely to get a lower grade.
There are a lot of posts on the PCGS blog which describe crossing coins from NGC to PCGS. The PCGS fans want their entire collection in those holders, or they are determined to participate in the PCGS registry which only accepts their products. In virtually every instance, those guys expect to get a lower grade when they cross their coins. If you got an up grade, you were an exception.